This invention relates to an optical connector and an endoscope provided with an optical connector.
An optical connector disclosed in FIG. 2 of U.S. Pat. No. 4,807,958 comprises a tubular connector body. One end portion of an optical fiber is inserted into and fixed to this connector body. A tubular retainer is threaded on the outer periphery of the connector body. This retainer has an annular flange formed on its inner periphery adjacent to its open distal end. A spherical lens (optical element) is received within the retainer. The spherical lens is disposed between the flange of the retainer and a conical surface formed on the distal end of the connector body, and is exposed to the exterior via the open distal end of the retainer. The retainer is threaded on the connector body until the spherical lens is brought into contact with the conical surface on the distal end of the connector body and the flange of the retainer, so that the spherical lens is firmly supported.
In the above optical connector, the spherical lens is firmly held between the flange of the retainer and the connector body, and therefore when the connector is not in use, the spherical lens exposed to the exterior, upon striking against a rigid object, may be damaged by an impact force. Also, there is a possibility that the spherical lens may be damaged by a thermal stress caused by the heat from a light source device. Although an O-ring of an elastic material is mounted within the retainer, this O-ring is used merely for sealing purposes, and does not perform any function of supporting the spherical lens.
An optical connector disclosed in U.S. Pat. No. 4,799,754 comprises a tubular connector body into which one end portion of an optical fiber is fixedly inserted, and a tubular retainer threaded on the outer periphery of the connector body. A flange is formed on the inner peripheral surface of the retainer intermediate the opposite ends thereof, and an annular holder plate is fixedly secured to the distal end surface of the retainer. Mounted within the retainer are a glass plate disposed between the flange and the holder plate, and a pair of O-rings disposed respectively on the opposite sides of the glass plate. In this optical connector, an impact against the glass plate can be absorbed by the pair of O-rings; however, since the glass plate is held between the pair of O-rings, the position of the glass plate relative to the end face of the optical fiber can not be maintained with high precision.
An endoscope disclosed in Japanese Laid-Open Patent Application No. 56-47014 comprises an endoscope body, a flexible insertion tube extending forwardly from the endoscope body and having at its distal end portion an illumination window and an inspection window, and a light guide tube extending laterally from the endoscope body. An optical connector of a cylindrical shape is attached to the distal end of the light guide tube. The endoscope further comprises an optical fiber bundle whose one end portion is inserted into and fixed to the optical connector. The optical fiber bundle is passed through the light guide tube, the endoscope body and the insertion tube, and is opposed at the other end thereof to the illumination window. As shown in FIG. 4 of the above publication, the optical connector comprises a tubular connector body into which the one end portion of the optical fiber bundle is fixedly inserted, a retainer threaded on the outer periphery of the connector body, and a cover glass plate fixedly mounted on an open distal end of the retainer. The cover glass plate serves to protect the one end face of the optical fiber bundle. The optical connector is inserted into a housing of a light source device, and in this inserted condition, the distal end of the optical connector is disposed in opposed relation to a light source. Illumination light from the light source is incident on the one end face of the optical fiber bundle via the cover glass plate, and is passed through the optical fiber bundle, and is emitted from the other end face of the optical fiber bundle into a body cavity via the illumination window.
In the optical connector of the above Japanese Laid-Open Patent Application No. 56-47014, also, since the cover glass plate is fixedly mounted on the retainer, this plate may be damaged upon striking against a rigid body or upon reception of a thermal stress. Constructions analogous to this optical connector are disclosed in Japanese Laid-Open Utility Model Application No. 56-66908 and Japanese Utility Model Publication No. 62-32243. In this Utility Model Publication No. 62-32243, instead of a cover glass plate, a fiber conduit is fixedly mounted on a retainer.
U.S. Pat. No. 4,953,937 discloses an endoscope in which a light guide tube is detachably connected to an endoscope body. Other prior art include U.S. Pat. Nos. 3,710,091, 3,724,383, 4,307,934, 4,846,544 and 4,850,669.
U.S. patent application Ser. No. 500,491 filed Mar. 28, 1990 and European Patent Application No. 90303515.2 (corresponding to this U.S. Patent Application) filed Apr. 2, 1990 disclose a connector for an endoscope which is analogous in construction to the present invention, but is not provided with an O-ring of an elastic material.